1. Field of the Invention
The present invention relates to a developer cartridge for housing toner and an image forming apparatus wherein the developer cartridge is attached to and detached from the image forming apparatus. More particularly, it relates to a developer cartridge and an image forming apparatus capable of communicating with each other.
2. Description of the Related Art
There has been known an image forming apparatus with a cartridge which is attached to and detached from the apparatus body and houses toner in its container. As typical examples of such cartridge, an imaging cartridge, a toner cartridge, and the like have been known. It is required for the image forming apparatus of this type to detect amount of residual toner in its cartridge at any time. Therefore, there have conventionally been applied a detection method by using a light emitter, a light receiving sensor, and a light guide as a set, or a detection method by using a reflecting sensor and a residual-toner-amount detecting window, or the like. Furthermore, JP Unexamined Patent Publication No. 2005-195791 discloses an image forming apparatus and a residual-toner-amount detecting method wherein contact state of a flexible film strip and a toner detecting electrode is detected to find out residual toner amount.
Some image forming apparatuses of the above-mentioned type have been designed on assumption that attachment and detachment of its cartridge is carried out by a user. It is required for such image forming apparatuses to prevent a cartridge mix-up and an erroneous insertion. For that purpose, some image forming apparatuses employ communication means between an apparatus body and a cartridge. Thereby, the apparatus body can receive information of the cartridge at the time of attachment and notify a user of an error in case of an erroneous attachment. For example, JP Unexamined Patent Publication No. 2002-169428 discloses a cartridge which is equipped with recording means such as IC chip or the like which enables the image forming apparatus to read information of the cartridge. According to the publication, the employment of recording means contributes to space saving design and design diversification.
However, in the above-mentioned conventional image forming apparatuses, residual-toner-amount detecting means and communication means as countermeasure for erroneous insertion are constituted separately. Both of them must be arranged inside or near inside of a cartridge. Furthermore, since it is required for them to secure a detection point, a communication path, and the like, positioning of them is restricted to some extent.
For example, in case an optical sensor is used as residual-toner-amount detecting means, any other composing members cannot be arranged on the detection line of the sensor. To secure detection accuracy of residual toner amount, it is required to secure positional accuracy of a holding member for holding the sensor or the like. It is desired that the communication means be arranged inside of a cartridge so as to prevent damage at the time of attachment. Furthermore, it is also required to arrange the residual-toner-amount detecting means and the communication means without intervention of each other.